The short answer
Read a heating curve for a substance you have never met — name the phase, rank the specific heats from the slopes, get the latent heats from the plateau lengths — and run a multi-leg energy calculation without dropping a leg.
Written and checked by GAMSAT tutors — not AI-generated.
Try the reasoning style
We treat forgetting as a failure — a lapse to be patched with reminders and records. Yet a mind that kept everything could not think; it would drown in the undifferentiated noise of every moment it had ever lived. To forget is not so much to lose information as to decide, mostly without our noticing, what was never worth keeping.
The author's argument relies most directly on which unstated assumption?
Pick an option to see how the tutor reasons to the answer — not just whether you were right.
Not quite — the answer is B.
Work backwards from the conclusion: a mind that ‘kept everything’ supposedly ‘could not think.’ That only follows if thinking means leaving most of experience out — so B is the premise the argument quietly rests on. A raises reliability, which the passage never weighs; C contradicts ‘mostly without our noticing’; D smuggles in a claim about intellect the passage never makes. The question rewards finding the hidden premise, not recalling a fact.
Section III will not ask you for water's latent heat. It hands you a heating curve for a substance it declines to name and asks where the energy is going. Arriving energy either makes particles move faster or pulls them apart: the first moves the thermometer, the second does not. Read the graph as ratios and the constants never matter.
Reading any heating curve
Name the phase first
Sloped = one phase warming. Flat = two phases coexisting; how far along the plateau you sit is the fraction that has changed.
Slope ranks the specific heats — upside down
Gradient = ΔT/Q = 1/(mc). One sample, so m is fixed and only c moves the slope: the steeper leg has the smaller c. Candidates read this backwards, because everywhere else steep means big.
A plateau's run IS the latent heat
It equals mL on the same axis as everything else, so latent against sensible, or one latent heat against the other, is a ratio you read straight off.
If the axis is TIME, check the power
Constant power means Q = Pt: a time axis is an energy axis rescaled, so every ratio survives and "3 minutes to warm, 30 to boil away" measures a latent heat. If the power varies, none of it holds.
Where the marks go
Bookkeeping fails people, not arithmetic: list the legs, each starting where the last finished. There is no ΔT on a plateau, and the liquid's c never enters the steam leg.
Worked example — five legs
A 20 g ice cube at −10 °C taken entirely to steam at 110 °C. c = 2.1/4.18/2.0 J g⁻¹ K⁻¹ (ice/water/steam); L = 334 and 2260 J g⁻¹.
Check yourself
A heater delivering energy at a constant rate warms a sample of a pure liquid from 60 °C up to its boiling point of 80 °C in 2.0 minutes, with no energy lost to the surroundings. The liquid's specific heat capacity is 2.0 J g⁻¹ K⁻¹ and its latent heat of vaporisation is 800 J g⁻¹. Once the sample reaches 80 °C, roughly how long does the same heater take to boil it away completely?
Key takeaways
- On temperature-against-energy the gradient is 1/(mc): the steeper leg has the SMALLER specific heat.
- A plateau is not a pause — its run is mL, and at constant power a stopwatch measures it.
- Five legs from solid below zero to gas above boiling; the failure is bookkeeping, and vaporisation dwarfs the rest.
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